Electric tempering



July 15 1924.

E. RAMON DO ELECTRIC TEMPERING Filed Feb. 2, 192.1

g 5 0 d e a... July 15, 1924.

"UNITED ST TES-- 1,501,369 PATENT OFFICE.

mom, or'runnr, ITALY.

nmcrmclrmmxe.

; Application am February 2, 1921. mm 10.441301.

Toall'whomitmay concern:

Be it known that I, Erronn RAMONDO, a subject of the King of Italy, andresident of Turin, in the Kingdom of Italy, have I invented certain newand useful Improveused for manufacturing springs and effecting thehardening and tempering operation. 2 The system for transformin theelectric energy into heat based on Jou es principle is already known.This invention is based on the same principle but, while in the usualtransformation of electric into thermicenergy the resistance of theapparatus efiecting such transformation is calculated in accordance withthe electromotive force of the available current, in this system theelectromotive force of the current varies in 80 agreement with the ohmicresistance opsedby the material to be treated and to its heat efiiciencyin respect of the temperagure (int which the treatment has to be efectes5, My process consists substantiallyin the use of a currenttransforming apparatus from high to a low tension, an arrangement forobtaining the various'voltages required in the seconda circuit, and anapparatus for inserting t e steel tobe treated mto the secondarycircuit. This invention is substantially characterized by means for Iregulating the current in accordance with 'the dia am obtained throughthe electromotive Tdrce and its strength and the'treat- .ment to whichthe steel will be submitted.

Numerous experiments have demonstrated that steels havin been submittedto the same thermoelectric treatment do not show identicalcharacteristics; these latter vary.

according'to the duration oithe' operation; this .occuri'n also11n theordinary thermic treatment. herefore it'is absolutely necessary bot froman economical and teclmsi l, cal point of view, to vary the currentcharto be a full, clear,

to flow through the spr make the process an economicalone.

acteristics in accordance with the requirements of each case.

If the steel has a very hi h specific electric resistance this mayproduce a considerable fall of potential between the ordinary currentconductors and the iece to be treated. However, owing to t e size ofsaid piece, its ohmic resistance may be practically and inmost cases ismuch lower than the ohmic resistance of the entire electric circuit inwhich the piece is inserted. Assuming that a steel bar measuring 1 m.

length and having a section of 200 sq. mm. is heated, its resistancewill be 0.0005 ohms,

while all the circuit, in an ordinary plant,

- has a resistance of about 0.0045 ohms, namely 9 times higher. Itistherefore necessary that the current strength be kept within certainlimits, in this case and for the different treatments from 6 to 10amperes for each sq. mm. of section, according to the section of theiece to be treated, so that the insertion oi the piece produces thedesired J oulels phenomenon. I The above said steel bar had a section ofabout 200 sq. mm. but a bar having a section of 50 sq. mini may have thesame ohmic resistance as the former one, as in the case of a springformed of wire of a section of 50 sq. mm. and 25 cm. length. It isevident that if the same-amount of electricity that was available -forthe bar having a section of 200 sq. mm. is caused this latter will notonly be heated but wi melt producing a short circuit. It would appearthat by insertin a subsidiary resistance into the circuit an suitablyvarying its value-in rela tion with the piece resistance, it would bessible to reduce the currentstrength acand therefore not at allconvenient and its oifice would be to absorb the surplus elec-' tricity.It is evident that in this-case the cost of the process is not inproportion with 5 the weight of the piece to be treated, but is constantfor each piece, whatever be its size, be it for, instance a bar 1 m.long and having a section of 200 sq. mm. or a round bar having a lengthof 0.25 m. and a section of'50 sq. mm, and this of course does not Bythe process form he object of this invention, the losses in t edifferent operations are reduced to those due to the apparatusefficiency and the current consumption is proportional to therequirements of each particular case, so that the highest efliciency isobtained and the process may be used for manufacturing purposes.

This result has beenobtained by means of, a transforming apparatustransforming the primary current having a very low volt-.

former and a series of identical transform-.

ing elements, the primary circuit of which is in series with theauto-transformer, while each element of its secondary circuit leads toterminals, by means of which and a special commutator it is possible tomount the'elements in series in parallel or in multiple series.

The auto-transformer and the primary windings of theunder-transformation elements are mounted in series on the mainconductor of the supply line in such a manner as to allow of a certainnumber of element pans to be cut out of the circuit in order to increasethe number of combinations. The secondary winding of each element leadsto two terminals, that, leaving each element in- I dividualized, allowof disposing by means of knife switches .and according to requirements,all the elements in parallel, in series or in multiple series.

Assuming to dispose of a current of 2000 volts and an auto-transformercapable of ten boosting voltages to 2200, 2400, 2600 up to 4000 volts,and each element giving a current transformed from 2000 volts to volts,it is evident that for each voltage of the auto-transformer an elementmay have different voltages of 5.5; 6; 6.5 up to 10.

By inserting 16 element pairs, it 1s possible to obtain all the desiredvoltages by suitably disposing said elements in such a manner as toobtain from 5 to 10 volts with a variation from half volt to half volt;of 10 to 20 with a variation from volt to volt;

I of '20 to 40 with a variation from 2 to 2 volts etc. By eliminatingone or more element pairs, it is moreover possible to .obtainintermediate voltages so as to realize a great number of combinationssatisfying not only all the work requirements, but also the eventualexperiment requirements, as it is necessary in this kind of work.

In the annexed drawing is shown, by way of example, a diagrammatic formfor the use of this process for the manufacture of hel- Evidently thesame rocess may also advantageously used or the manufacture ofsemi-elliptical and elliptical springs.

To the main primary conductors C is connected an auto-transformer A, thesecondary circuit of which is branched from one of the terminals of thewinding aand one of the intermediate points 6, c, J, 6 by means of aninterrupter or ordinary switch M or the like. In the secondary circuitof the auto-transformer A is mounted the transformer T, the primary ofwhich is divided into of mounting all the elements in series or inparallel or, by their combined action, some element groups in series,according to requirements.

In the circuit S of the secondary ofthe transformer T is suitablyinserted the starting rheostat R by means of an interrupter N and thepiece D to be treated; this latter is preferably connected with theterminals F, allowing of the free expansion of said piece. I

In the main primary circuit C is finally inserted an automatic minimumcut out P the electromagnet of which is operated from any suitablecurrent source, for instance, as shown in the drawing, from the lightingmain L to which its winding is coupled in parallel by means ofconductors O. In said conductors are inserted: an interrupter '1: and apress switch v situated near the piece D to be treated so as to bewithin reach of the operator charged with the heating of and 'v andtherefore the automatic inter- 'or not and the arrangement willagain bein condition for operation.

When the work is finished, the current flowing to the main circuit isfinally cut out by opening the interrupter i and the dividing knives Z.

In this arran ement either by operating the interrupter of theauto-transformer, or by mounting in series or in parallel or in multipleseries all or some of the elements of the secondary of the transformer Tby means of the interrupters I, and 1,, it is possible to-control thestrength of the current to be fed to the steel iece under treatment inorder to obtain t e desired result.

Claims: 1. In the art of tempering, transforming alternating current,re-transforming the transformed current and simultaneously proportioningthe re-transformedcurrent to give an amperage suited to differentlengths, cross-sections and weights of the work through which there-transformed current asses. 2. In the art of tempering, transformingby step up auto-transformation alternatin current, re-transforming thetransform current downward and simultaneously proportioning suchretransformed current to give an amperage suited to the requirements ofdifferent lengths, weights and cross-sectioi: of the'w'ork through whichsuch retrafisformed current passes. i

3. In the art of tempering, transforming alternating current,re-transforming the transformed current and simultaneously proportioningthe voltage of the re-transformed current to give an amperage suited tothe requirements of the work through which the retransformed currentpasses and f 'beparately controlling the Volta of the 30 current passingthrough the wor 4. In the art of tempering, transforming by step upauto-transformation .alterat' current, re-transformin the transforn i dtl current downward and simultaneously pro- '3 portioning the voltage ofsuch retransformed current to give an ampera suited to the requirementsof different lengths, v

weights and cross-sections of the work through. which such retransformedcurrent passes, and separately controllin the voltage of the currentpassing throng the work.

5. In, electric tempering A apparatus, an v auto-transformer, means tota e therefrom current of different values, a second transformer havinga primary winding supplied with such current and a plurality oelectrically interconnecti-ble secondary windings and means to supplycurrent from said secondary windings.

6. In electric tempering apparatus a stepup'auto transformer means totake therefrom currents of different values, a second step-down.transformer supplied with such currents and comprising a primarywindingand a plurality of secondary windings, means to variously connectsaid secondary windings to proportion the current to the work and arheostat in circuit with said' second transformer and the work.

7. In electric tempering apparatus a stepup auto transformer means totake therefrom currents of different values, a second step-downtransformer supplied with such currents and comprising a primary windingand a plurality of seconds windings, means to variously connect andsecondary windings to proportion the current to the work and a rheostatin circuit with said second transformer and the work, and means at thework to disconnect the auto 70 transformer from the line.

In testimony that I claim the forego ng as my invention, I have si ed mname.

ETTOB R ONDO.

